1. Field of the Invention
The present invention relates to a cylinder apparatus capable of clamping a workpiece by using an arm which is rotatable by a predetermined angle in accordance with a displacement action of a piston.
2. Description of the Related Art
The cylinder apparatus has been hitherto used, for example, in order to clamp a constitutive part when the constitutive part of an automobile or the like is welded. Such an cylinder apparatus is disclosed, for example, in U.S. Pat. No. 4,905,973.
The cylinder apparatus disclosed in U.S. Pat. No. 4,905,973 is constructed as follows. That is, its main body is constructed by integrally combining a pair of casings which are formed substantially in a mutually symmetric manner. A cylinder unit is coupled to the main body. An arm is rotated by a predetermined angle by the aid of a toggle link mechanism provided at the inside of the main body in accordance with the driving action of the cylinder unit.
The toggle link mechanism includes a lever arm which is rotatable by a predetermined angle about a center of a rotation pin. The lever arm is provided with a stopper for making abutment against the inner wall surface of the casing to stop the rotary action of the arm when the arm is used to clamp a workpiece.
However, in the cylinder apparatus concerning the conventional technique disclosed in U.S. Pat. No. 4,905,973, the stopper for stopping the rotary action of the arm is provided at the inside of the casing. For this reason, it is necessary to disassemble the casing when the maintenance operation is performed for the stopper. Therefore, an inconvenience arises in that the maintenance operation for the stopper is complicated, and it cannot be performed efficiently.